1. Field of the Invention
The invention relates to a power supply device, and more particularly, to an expandable power supply system generating a supply voltage by utilizing one or more power supplies selectively.
2. Description of the Related Art
With the development of the science and technology, electronic products become more and more popular. The computer is very favored due to its diverse functions. For example, the computer may satisfy all requirements on different aspects such as work, travel, and entertainments, and it also may be used for processing personal financial details, privacy documents and photos, commercial documents, and intellectual work for users.
The supply of power is very important when the computer is used. Generally speaking, the computer must cooperate with a proper power supply in assembling according to its power consumption. The power supplies are mainly used for converting alternating current (AC) voltage to direct current (DC) voltage needed by the computer. Afterwards, the voltage converting unit of the computer utilizes the DC voltage outputted by the power supply to orderly generate the supply voltages needed by different components of the computer.
However, along with the innovation of electronic products, when the user upgrades the functions of the components in the computer by reassembling the computer, an old power supply always cannot provide enough watts to the upgraded computer. At that moment, the user always has to buy a new power supply with larger watts to meet the requirement of the upgraded computer. Consequently, not only a hardware cost is increased when the computer is upgraded, and the resource is wasted when an undamaged power supply is replaced.